John Terraine, who has died aged 82, was a prolific military historian whose reputation was based mainly, but by no means exclusively, on his numerous publications on the first world war, and particularly the war on the western front. His outstanding achievement in television was the BBC's groundbreaking 26-part series The Great War, in which in 1963-64 he had a dominant role as associate producer and principal scriptwriter.
His strong opinions were evident from the subtitle of his first book, Mons: The Retreat To Victory (1960). Three years later, he provoked intense controversy with the publication of Haig: The Educated Soldier, which was sharply at odds with the popular view that the first world war had been the supreme example of "mud, blood and futility", with British generals depicted as callous, obstinate and incompetent. Terraine was by no means an uncritical apologist for Sir Douglas Haig, but he placed the British commander-in-chief and the British army's achievement in the wider context of modern industrialised warfare, arguing that the strength of the German army and the confined conditions on the western front made a long war of attrition unavoidable.
He showed, moreover, that from a small, under-equipped force in 1914, the British army had developed into the vast, efficient and well-led instrument that had played the major role in securing victory in 1918. Haig, in his view, deserved great credit, not only for persevering through the costly campaigns of 1916 and 1917, but also for resisting the political machinations of the prime minister, Lloyd George, who lacked confidence in him and would have liked to remove him.
Though a sensitive, emotional man acutely vulnerable to criticism, Terraine was also a bold and indefatigable controversialist, defending his views in the newspaper letter columns and in reviews, articles and a remarkable output of books. Critics pointed out that he relied too heavily on standard publications as distinct from archival research, and was inclined to repeat himself; that his tone became increasingly polemical on some critical issues; and that his deterministic overview of the nature of war on the western front was inconsistent with his stress on the British army's tactical and technological innovation under Haig's direction. Nevertheless, while some historians still differ from Terraine on specific issues, such as his hostile attitude towards Lloyd George, he deserves praise for persevering when he was almost alone in his positive view of Haig's conduct of the war. In this respect, professional military historians have broadly come round to his way of thinking, even if it remains at odds with public opinion.
Terraine was born in London, and educated at Stamford School, Lincolnshire, and Keble College, Oxford, of which he was elected an honorary fellow in 1986. Between 1944 and 1963 he worked for the BBC, first as a recorded programmes assistant, and later programmes organiser for the World Service at Bush House, before turning freelance with the publication of his book on Haig.
From 1966 to 1968 he wrote and presented Thames television's award-winning series The Life And Times Of Lord Mountbatten, and in 1974-75 was the scriptwriter for BBC television's The Mighty Continent, a history of Europe in the 20th century.
In the 1980s, the focus of his work shifted from television to written history. In 1985 he won the Yorkshire Post book of the year award for The Right Of The Line: The Royal Air Force In The European War, 1939-1945, in which he was surprisingly critical of the attritional strategy of Bomber Command: to some reviewers, it seemed a logical development of Haig's earlier strategy.
In 1989 he published Business In Great Waters: The U-Boat Wars, 1916-1945, which enabled him to portray the world wars against Germany as part of a continuous struggle, and to display his mastery of the technological side of warfare - a theme explored earlier in his last book about the first world war, White Heat: The New Warfare, 1914-1918 (1982).
While in public debate Terraine could sometimes appear opinionated, choleric and even blimpish, his views were sincerely held, and in private he was convivial, humorous and a lively conversationalist. In 1982, he was awarded the prestigious Chesney Gold Medal by the Royal United Services Institute for Defence Studies, and in 1987 he was elected a Fellow of the Royal Historical Society.
In 1945 Terraine married Joyce Waite: their daughter, Carola, followed in her father's career as a historian. In later years, after the marriage had broken up, he found a devoted companion in Kathy Stevenson, who helped him in building up the Western Front Association - of which he was founding president (1980-97) and then patron - and in prolonging his active career despite a crippling illness. She and his daughter survive him.
· John Alfred Terraine, historian, born January 15 1921; died December 28 2003
